A group of women drink tea under the shade of a tent and cast an eye over the construction of an odd, circular house. The half-built dwelling is the brainchild of Tateh Lehbib Braica, 27, an engineer who wanders among the workers.

On the ground lie hundreds of sand-filled, 1.5 litre plastic bottles that serve as bricks. With them, Tateh has found a way to fight back against the harshness of the Algerian desert that is home to 90,000 long-term refugees from western Sahara. It’s not yet that hot, but in summer, when the temperature rises above 50C, it will be impossible to venture out of doors.

“I was born in a sun-dried brick house,” he says. “The roof was made of sheets of zinc – one of the best heat conductors. Me and my family had to endure high temperatures, rain and sandstorms that would sometimes take the roof off.

The houses possess several qualities that equip them for the brutal ecosystem of the Algerian hamada, the so-called desert of all deserts. The walls are made of sand-filled plastic bottles, cement and a mixture of earth and straw that acts as thermal insulation. Compared with the traditional sun-dried bricks, which fall apart in the rains that batter the region from time to time, they are very tough.

Their circular shape serves a dual purpose: not only does it stop dunes forming during sandstorms as happens with square houses, it also – along with the white-painted exterior – reduces the impact of solar rays by up to 90%.

A double roof with a ventilation space and two windows set at different heights to encourage air flow mean that temperatures are 5C lower than in the other houses in the camps.

The floods of 2015 and 2016 destroyed 9,000 homes and 60% of the camps’ already scant infrastructure, according to the UN refugee agency, UNHCR.

Tateh’s idea reached the UNHCR’s Geneva HQ and it was selected as a pilot project. The agency’s grant of about €55,000 (£43,000) has seen 25 more houses built in the five Sahrawi refugee camps in the Algerian province of Tindouf.

Tateh’s circular homes have sprung from the ground in the camps of El Aaiún, Auserd, Smara, Bojador and Dajla, all of which are named after the western Saharan cities from which thousands of people fled in 1975 after the so-called Green March and Moroccan occupation.

Much of the scheme’s success lies in its low-cost and ecological benefits. Each house needs about 6,000 bottles and takes a team of four people a week to build.

“We don’t have modern recycling like they do in other countries, but we can make use of all the tonnes of plastic,” says Tateh, who studied renewable energy at Algiers University followed by a masters in energy efficiency at the University of Las Palmas in Gran Canaria thanks to an Erasmus Mundus grant from the EU.

“The idea came to me in 2016 after the big flood,” he says. “I was using plastic bottles to make a mock-up of some roofs and it just hit me.”

According to Hamdi Bukhari, the UNHCR’s representative in Algeria, “the project is really innovative and beneficial, not just for the people who live in the houses but also when it comes to providing work and for the environment.”